On 17/03/14 12:26, [email protected] wrote:
Hi Dave,
That is an enormous shame. This is a methodology I've worked with in a
different library and it makes a very simple way to instantiate complex
structures from tabular structures.
For instance consider this pseudo code below, it reads a three column CSV file,
then it creates URIs for objects and combines these URIs and attributes in the
forward chaining bit. This both loads and denormalizes the serialized object
structure back into a graph / tree.
[loadable:
Load(“/mytable.csv”, ?customerName, ?customerAccount, ?service)
makeURI(?custObj, ns:, ?customerAccount )
makeURI(?serviceObj, ns:, ?service)
->
(?custObj a ns:CustomerAccount)
(?custObj ns:customerName ?customerName)
(?custObj ns:customerAccountId, ?customerAccount)
(?custObj ns:customerHasService ?serviceObj)
(?serviceObj a ns:Service)
(?serviceObj ns:serviceId ?service)
]
I am sure you can see that this method can be applied to lots of different
scenarios and is a very simple way to load bindings and immediately create a
graph from those bindings.
Do you know of other libraries that might support such operations?
Seems like all you need to do here is instantiate some triple patterns
based on bindings from a data source.
That's pretty straightforward to do directly. I'm not sure the rules
engine would really help you much, you wouldn't be using rule chaining
in any case and the syntax for the rules is hardly friendly :)
I'd be inclined to just use a template instantiation approach. The
templates could be e.g. SPARQL update or some custom syntax.
Typically the only tricky bit of template-based approaches is all the
processing builtins that you want for string mangling etc. I've
typically used embedded ruby or javascript for that in the past though
have recently [1] have used the lighter-weight Apache jexl [2] with some
success.
Dave
[1] https://github.com/epimorphics/dclib/wiki
[2] http://commons.apache.org/proper/commons-jexl/
Cheers,
Richard
Sent from Surface Pro
From: Dave Reynolds
Sent: Monday, March 17, 2014 12:13 PM
To: [email protected]
On 17/03/14 11:44, Richard Morgan wrote:
Hi Dave,
Thank you for your response, I'm glad to have my thoughts confirmed. Is it
possible to write my own generators and register them like I have with
builtins?
No, sorry.
For the forward rule system there's simply no equivalent notion.
For the backward rules there is the notion of generators but they aren't
designed as an extension point (far from it).
The problem I want to solve isn't the regex example above, its more about
generating bindings so I can feed them into a forward rule and then
instantiate triples as a general pattern.
Hard.
You can write builtins which assert information directly into the
deductions graph which can generate as many triples as you want. That's
relatively easy and safe. However, it bypasses all the rule machinery
and means that other rules don't see the results and you don't get to
instantiate more patterns.
It might just be possible to write a builtin which would directly call
the rule engine to add a rule firing to the conflict set
(RETEEngine.requestRuleFiring) and pass in a series of different
manufacturing binding environments to each firing request.
However, I've never tried anything like that and prodding the underlying
engine mechanics from within a builtin is not guaranteed to be safe!
Dave
Cheers,
Richard
On Mon, Mar 17, 2014 at 9:06 AM, Dave Reynolds <[email protected]>wrote:
On 14/03/14 13:53, Richard Morgan wrote:
Hi,
I would like to extend the base regex function in Jena to provide more
than
one match result.
I don't think that's possible.
For instance I would like the following rule
[ myregex("the cat sat on the mat", \"(.at)\", ?token)
" -> (<http://a> <http://b> ?token)]";
to return
- [http://a, http://b, "cat"]
- [http://a, http://b, "sat"]
- [http://a, http://b, "mat"]
From looking at how BindingEnvironment works I can only return with a
single binding per variable.
Correct.
In Jena rules then builtins are only used as essentially filters on rule
firings, they aren't generators.
In the forward rule case (which is suggested by your notation above) that
wouldn't make sense anyway - forward rules either fire or they don't,
there's no backtracking.
In the backward rule case then there is backtracking but the interface for
builtins doesn't support their use as generators.
Dave
